MOT fail!

[imp124]

Hi

My ST failed its MOT today but only on emissions

i have found the CO should be 3.50% max at idle but mine was 5.20%

I gave the car a good run upto the MOT centre and they even tested it twice just to be sure, i cant see any intake leaks, the only things i can think of are the oxygen sensor (universal type which i think was a spare from the super s) and the ignition timing that i set myself which could be wrong.

can anyone help in explaining about the o2 sensor (i have been told it should equal 1 but on what setting on a multimeter?)

Also what should the ignition timing be set at (i thought i had it at 15 deg BTDC)

Anything else it could possibly be?

Apart from that he commented on how clean it was underneath with no rust what so ever

Cheers, Steve

 

[Guy]

I'd gues that was 1 volt DC Steve. I know it pulses but it should show as an average figure on a voltmeter.

 

[imp124]

ok cheers going to check all this tomorrow

 

[frank]

my readings were .... fluctuating between .4 and .6v at cruise steve, near zero on lift, and around .9v under acceleration :grinning:

 

[getawaycar]

The O2 sensor switches between rich and lean, thats what the pulsing is. Ideally an Oscilliscope should be used to test it. Failing that, couldn't someone lend you a spare to try?
To be honest, the O2 sensor is only one sensor that can affect the emissions. Temp sensors, map sensors etc. can influence it too.
Doesn't the ST have a carb? Couldn't the tester just have turned it down to pass?

 

[imp124]

The O2 sensor switches between rich and lean, thats what the pulsing is. Ideally an Oscilliscope should be used to test it. Failing that, couldn't someone lend you a spare to try?
To be honest, the O2 sensor is only one sensor that can affect the emissions. Temp sensors, map sensors etc. can influence it too.
Doesn't the ST have a carb? Couldn't the tester just have turned it down to pass?

Nope im afraid the ST has fuel injection :S

 

[getawaycar]

Nope im afraid the ST has fuel injection :S

So it will have a version of the ECCS injection? I'm not very familiar with STs!:laugh:
I have seen problems with running rich with 200SXs (which use ECCS) caused by leaky vacuum pipes. Usually, especially with Turbo cars the ECU will sense the car is running lean because of the vacuum leak and over compensate.

 

[Baz]

The st also has a CO adjustment at idle on the airflow meter (only found this out recently thanks to Ed)

My cat is out and the CO was 3.2% at idle

Might be a lambda, take it out with a 22mm spanner and shake it , if it rattles its gone, mine eats them every couple of track days!
As regards to the timing its spot on 15 degs is grand

You can see in the pics the adjuastment on the AFM this will need to be adjusted with an emmisions probe in the exhaust.

 

[imp124]

Cheers Baz,

just had the lamda sensor out and yes it rattles inside, i have a spare universal one which i dont know if it will do the job?

i tested this one with the engine running breifly and recorded 0.4v fluctuating and it was getting higher as it was warming up it seemed, but it started to rain before it could warm up, do i need to let if warm up completely before it will switch?

also the rear brakes failed too but it looks like the rear shoes have plenty of meat on them and they move and adjusted great but the material on them just crumbles very easily!

cheers

Steve

 

[Guy]

Pretty sure you can get replacement lambda sensors off ebay. Mine got an advisory for each back brake on my MOT a couple of weeks ago. Haven't had a chance to look at them yet, had to buy a 30mm socket to get the hub nuts off .

 

[imp124]

Just checked the timing too and its spot on 15 BTDC going back to the garage tomorrow and see what they say

 

[imp124]

PASSED! today no advisorys, didnt need any parts for the brakes just cleaning up, and the emissions screw was turned slightly apparently and given a good run and passed no problem. very happy. just a little worried if it runs too lean on s/c and turbo now? :S

 

[Baz]

PASSED! today no advisorys, didnt need any parts for the brakes just cleaning up, and the emissions screw was turned slightly apparently and given a good run and passed no problem. very happy. just a little worried if it runs too lean on s/c and turbo now? :S

No man it only changes the fueling for the emmissions at idle so it wont go lean

Congrats btw !!!

 

[r-reg-sr]

good show

 

[imp124]

im really glad for another year servicing it tomorrow and hopefully getting all that sorted